Sour Gas Handling Compliance

Permitting options and guidance relating to oil and gas sites that handle or produce ‘sour’ gas.

While the regulation of oil and gas activities in Texas falls primarily under the jurisdiction of the Railroad Commission of Texas (RRC), TCEQ regulates air emissions resulting from these activities. Of specific focus in this webpage are hydrogen sulfide (H2S) emissions from oil and natural gas handling and production sites. Owners and operators of these sites must obtain a TCEQ air authorization.

Definition of Sour Gas

Operations related to oil and gas wells are designated as sweet or sour depending on the concentration of H2S. The RRC’s Statewide Rule 36 imposes certain additional requirements when the concentration of H2S is equal to or greater than 100 parts per million (ppm). [Title 16 Texas Administrative Code Section 3.36 (16 TAC 3.36)]

TCEQ designates operations as sour if the concentration of H2S contains more than 1.5 grains per 100 cubic feet, or more than 30 grains of total sulfur per 100 cubic feet. This quantity is the equivalent of approximately 24 ppm, well below the 100 ppm RRC threshold. [30 TAC 101.1(96)]

While a site may be below the RRC's H2S threshold, it could still meet the TCEQ threshold. If the concentration of H2S at a site meets or exceeds TCEQ’s definition of sour, the operations are subject to increased regulatory requirements.

It is the owner or operator’s responsibility to ensure that each site complies with all applicable regulations and apply the 24 ppm level to their determinations for sour gas compliance with TCEQ.

Maintaining Compliance

As oil and gas wells age, the H2S levels of fields where they are located may increase. To ensure ongoing compliance, owners and operators are strongly encouraged to periodically review the current H2S concentration representations to determine if sites are keeping sour gas below the 24 ppm H2S threshold.

While there are numerous methods to demonstrate if a site is not handling sour gas, TCEQ encourages sites that have a H2S gas analysis greater than two years to perform a H2S concentration gas analysis of the product to ensure compliance under the proper authorization. If your site is handling or producing sour gas per the TCEQ definition, you will be subject to increased regulatory requirements, dependent on the site’s specific type of air permit.

Permitting Options

TCEQ has developed a tiered approach to provide more options for permitting oil and gas facilities that include: de minimis exclusion; historical authorization; permits by rule; standard permits; and case-by-case (New Source Review) permits.

Standard Historical Exemption

Permit by Rule

Certain oil and gas handling and processing facilities may be eligible for coverage under the Permit by Rule in 30 TAC 106.352 if they are not authorized under the de minimis rule or a historical standard exemption.

Facilities located outside the Barnett Shale counties and that are handling sour gas are required to meet the following:

One-quarter mile distance from any recreational area, residence, or other structure not occupied or used solely by the owner or operator of the facility or the owner of the property upon which the facility is located. [30 TAC 106.352(l)(3)]

Register with TCEQ via STEERS and include all necessary supporting documentation showing that all requirements of the PBR will be met. [30 TAC 106.352(l)(5)]

Facilities located within counties in the Barnett Shale (Cooke, Dallas, Denton, Ellis, Erath, Hill, Hood, Jack, Johnson, Montague, Palo Pinto, Parker, Somervell, Tarrant, and Wise) are required to comply with the requirements of 30 TAC 106.352 subparts (a-k) of the Permit By Rule.

Find additional guidance information on this PBR at TCEQ's Air PBR 106.352 webpage.

Depending on the operating scenario, other PBRs may be applicable to the facility.

Standard Permit

If facilities cannot meet the requirements in the Permit by Rule, they may be eligible for coverage under the Standard Permit in 30 TAC 116.620. The Standard Permit has additional requirements for facilities with fugitive emissions or using field gas for combustion, if the gas is sour.

Facilities handling or processing sour gas and located less than ¼ mile from the nearest off-plant receptor:

H2S fugitive emissions are prohibited unless the equipment is inspected and repaired as per subsection (c)(3) of the standard permit. [30 TAC 116.620(a)(11)]

Facilities handling or processing sour gas and located more than ¼ mile from the nearest off-plant receptor:

H2S fugitive emissions are prohibited unless the equipment is inspected and repaired as per subsection (c)(3) of the standard permit OR

H2S emissions are monitored with ambient property line monitors as per subsection (e)(1) of the standard permit. [30 TAC 116.620(a)(11)]

If using sour field gas for combustion units and flare pilots, the operator must maintain records, including at least quarterly measurements of fuel H2S and total sulfur content, to demonstrate compliance with emissions limitations as set by the standard permit. [30 TAC 116.620(a)(18)]

Exception: If a flare is the only combustion unit on a property, the operator is not required to maintain such records on flare pilot gas.

Facilities must use Tutweiler analysis or equivalent to determine the H2S content. [30 TAC 116.620(d)(2)]

Non-Rule Standard Permit

Facilities within the Barnett Shale constructed or modified after April 1, 2011, are subject to the requirements of subsections a-k of this permit. Requirements specific to the handling of sour gas are:

Fuel Records: If sour field gas is used, the operator must maintain records, including at least quarterly measurements of fuel H2S and total sulfur content, which demonstrate that the annual SO2 emissions do not exceed limitations.

Atmospheric Oil or Water Separators: If H2S can exceed 24 ppm in the vapor space, the separator vent must be captured and directed to a control device listed in the Control Device Best Available Control Technology Table with a minimum design control efficiency of at least 95%.

All impacts evaluations must be completed on a contaminant-by-contaminant basis (including H2S) for any net emissions increases resulting from a project and must meet the limits specified in section (k) of the permit.

All new projects and dependent facilities not located in the Barnett Shale counties are subject to subsection l of this permit and are held to the requirements of Standard Permit 116.620. For projects located outside the Barnett Shale counties which are constructed or modified on or after April 1, 2011, companies may voluntarily register under the new requirements in (a)-(k).

Case-by-Case (New Source Review) Permits

If a facility cannot meet the requirements of the Permit by Rule or the Standard permits, then they must authorize their site using one of the other available individual or “case-by-case” air permits. You can find information on these permits and their applications at the New Source Review Application Tools webpage.

Texas Environmental, Health, and Safety Audit Privilege Act

The Texas Environmental, Health and Safety Audit Privilege Act (Audit Act) may be helpful to certain facilities that are unsure of their compliance status. The Audit Act provides certain immunities from administrative or civil penalties for violations voluntarily disclosed and corrected within a reasonable amount of time. Learn more about the Audit Act.